Abstract
A simple field theory approach is developed to model the properties of charged, dielectric bodies and their associated counterions. This predictive theory is able to accurately describe the properties of systems (as compared to computer simulation data) from the weak-coupling limit, where the Poisson-Boltzmann theory works well, through to the strong-coupling limit. In particular, it is able to quantitatively describe the attraction between like-charged plates. In addition, the theory remains accurate even in the presence of dielectric bodies, properly accounting for the influence of image charge interactions. The theory is compared to the strong-coupling expansion, which is found to be applicable only in certain limited situations when dielectric variations are present.